The latest Broadband wireless data network technology development, including WiFi (802.11), WiMAX (802.16e) and DSRC (802.11p) technology, is progressing to large scale and full mobility. To support full mobility, various handoff (HO) procedures have been defined. Primarily, three handoff technologies are being developed:
1) Soft handoff (SOHO): SOHO is a make-before-break approach. In SOHO, an ASN (Access Service Network) anchor point device multicasts the same data flows to both a serving base station (base station) and all potential target base station. The mobile station (mobile station) has a selector to decide which target base station it is going to talk to when it moves from the serving base station to the next base station. An advantage of SOHO is that there will be no data packet loss during handoff because the same packets have been sent to the new target base station before the mobile station attaches to that new base station. A disadvantage for SOHO is that additional system resources (buffers, CPU, bandwidth, and air spectrum) are required to support the multicast data flows.2) Hard handoff (HDHO): HDHO is a break-before-make approach. In this case, a mobile station just simply drops a connection with the current serving base station, and re-establishes a new connection with a new target base station. During handoff, all the packets that were previously sent to the serving base station are lost, and the service flow has to be re-created using higher layer protocols. For example, where TCP is employed, the TCP layer would drop the original session and rebuild a new session. An advantage of HDHO is that it is simple and does not cost much in terms of system resources. A disadvantage is that the data path interruption may last up to 100+ ms to seconds. This leads to packet loss that can dramatically impact application performance.3) Fast Base Station Selection: With this approach, fast selection between a serving base station and a target base station is performed to support handoff and reduce the packet loss. The faster the selection speed is, the less packet loss is suffered, and the closer the performance is to that of SOHO. The slower the switching performed with fast base station selection, the closer the performance is to that of HDHO. Fast base station selection is also referred to in section 3.7.6 of a 802.16-2005 document as follows:                The mobile station (mobile station) is only transmitting/receiving data to/from one of active base station (anchor base station) at any give time. The anchor base station can change from frame to frame depending on the base station (base station) selection schema.        